Methods, systems and apparatus for relieving pressure in an organ

ABSTRACT

Methods, systems and apparatus for relieving pressure in an organ such as, but not limited to, the eye are disclosed. The method includes implanting a bioabsorbable, channel into the selected area of the organ using a delivery apparatus.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 60/806,402, filed Jun. 30, 2006, the entirecontents of which is hereby incorporated by reference.

BACKGROUND

The present disclosure generally relates to methods, systems andapparatus for relieving fluid pressure from an organ such as (but notlimited to) the eye. More particularly, the present disclosure relatesto methods and apparatus for treating glaucoma by relieving the pressurewithin the eye.

Glaucoma is a disease of the eye that affects millions of people.Glaucoma is associated with an increase in intraocular pressureresulting either from a failure of the eye's drainage system toadequately remove aqueous humor from the anterior chamber of the eye orthe overproduction of aqueous humor by the ciliary body. The build-up ofaqueous humor and resulting intraocular pressure can cause irreversibledamage to the optic nerve and the retina, which may potentially lead toirreversible retinal damage and blindness.

Presently, glaucoma can be treated in a number of different ways. Themost widely practiced treatment of glaucoma involves delivery of drugssuch as beta-blockers or prostaglandins to the eye (typically in theform of eye drops) to either reduce the production of aqueous humor orincrease the flow of aqueous humor from the anterior chamber of the eye.Glaucoma may also be treated by surgical intervention such astrabeculectomy. Trabeculectomy or similar surgical procedures involvecreating conduits between the anterior chamber and the variousstructures involved in aqueous humor drainage such as Schlemm's canal,the sclera, and the subconjunctival space in order to provide a pathwayfor the aqueous humor to exit the anterior chamber.

While these methods of treating glaucoma have been generally effective,they are not without their drawbacks. In the case of medicinaltreatments of the eye, patient compliance is an issue because suchtreatments require regular (i.e., daily) intervention. With respect tosurgical procedures such as a trabeculectomy, such procedures are veryinvasive and can cause irreversible changes to the eye. For example,trabeculectomy results in the permanent removal of a segment of thetrabecular meshwork, inflammation and scarring in the quadrant of theeye where the surgery was performed, and the formation of a filteringbleb. Implantation of shunts such as the Molteno, Barveldt, or Ahmedshunts induce chronic foreign body reactions and the formation of achronic subconjunctival bleb. In addition, such surgical treatment ofglaucoma often requires long healing times and can result in certaincomplications such as infection, scarring, hypotony or cataracts.

More recently, less invasive surgical treatments have been developed.These treatments do not require incision into the conjunctiva of theeye. One example of a less invasive surgical procedure is described inU.S. Pat. No. 6,544,249, the entire disclosure of which is herebyincorporated by reference. U.S. Pat. No. 6,544,249 discloses methods andapparatus for introducing a small bioabsorbable and biocompatibledrainage canal, referred to therein as a microfistula tube into theportion of the eye that extends from the anterior chamber to thesub-conjunctival space. The procedure described in U.S. Pat. No.6,544,249 does not require incision of the conjunctiva. Instead,introduction of the bioabsorbable microfistula tube is accomplished byan ab interno approach—through the cornea of the eye to the desiredlocation (between the anterior chamber and the sub-conjunctival space.)U.S. Pat. No. 6,544,249 also generally describes a delivery apparatusfor introducing and implanting the bioabsorbable microfistula tube.

U.S. Pat. No. 6,007,511, the entire disclosure of which is incorporatedherein by reference, likewise discloses less invasive methods andapparatus for treating glaucoma. As in the above-referenced U.S. Pat.No. 6,544,249, a bioabsorbable drainage tube is introduced into the areabetween the anterior chamber and the sub-conjunctival space to allowdrainage of the aqueous humor from the anterior chamber of the eye. Asin U.S. Pat. No. 6,544,249, incision of the conjunctiva is not required.

These new procedures for treating glaucoma offer the promise of a longterm cure of glaucoma without the shortcomings of medicinal treatmentsand without the risks associated with the known and presently practicedsurgical procedures described above. Accordingly, it would be desirableto provide improved methods, systems, channels and delivery apparatusfor treating glaucoma specifically and for treating other conditionswhere drainage of accumulated liquid is desired or required.

SUMMARY

The present disclosure sets forth improved methods and apparatus forcarrying out channel implantation into an organ of the body such as theeye. It will be appreciated that the methods and apparatus describedbelow may also find application in any treatment of a body organrequiring controlled drainage of a fluid from the organ. Nonetheless,the methods and apparatus for performing such treatment will bedescribed relative to the eye and, more particularly, in the context oftreating glaucoma.

The present disclosure relates to an implantable, microfistula channel.The channel has a bioabsorbable body defining an interior flow path. Thechannel body is made of cross-linked bioabsorbable material such asgelatin and has an expandable outer diameter. The flow path has adiameter of between approximately 50 and 250 microns (μm).

The present disclosure also relates to a method of making an implantablechannel. The method includes providing a source of a bio-compatiblegelatin solution and providing a generally cylindrical solid support.The support has a diameter of approximately 50 to 250 microns. Themethod includes contacting the outer surface of the support with thegelatin for a period of time sufficient to coat the support outersurface. A hollow gelatin tube is thus formed on the support. The formedhollow gelatin channel may be dried (cured) for a selected period oftime and the formed gelatin tube may be subjected to a cross-linkingtreatment. The formed and cross-linked gelatin tube is removed from thesupport.

The present disclosure also relates to an implantation apparatus forimplanting a channel into an organ of a subject. The apparatus includesa reusable portion that includes an apparatus housing. The housing hasan open distal end, a proximal end and an interior chamber. Theapparatus includes an arm subassembly within the housing that includesone or more movable arms adapted to engage a disposable needle assembly.The apparatus further includes one or more drivers coupled to said oneor more moveable arms of the arm sub-assembly.

The present disclosure further relates to systems for implanting achannel into an organ of a subject. The system includes a reusableportion adapted to receive a needle assembly and a disposable portionthat includes a needle assembly. The needle assembly has a hollow needleterminating in a sharpened tip and a guidewire and a plunger disposedwithin the needle. The system includes a microprocessor-based controllerincluding pre-programmed instructions for selective movement of at leastthe guidewire and the plunger.

The present disclosure further relates to methods of implanting abioabsorbable channel into an organ of a subject. In the methodsdescribed herein, an implantation apparatus including a hollow needlehaving a pointed distal end, a bioabsorbable channel within the needleassembly and a plunger proximally located relative to the channel isprovided. The method includes the steps of introducing the pointed tipof the needle end assembly into the organ of a subject, advancing theneedle to the desired area of implantation and actuating the plunger toadvance the channel to the desired area of implantation. The methodfurther includes removing the needle from the organ.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, depicts, in general, a method for implanting a channel, showingin cross section, the distal end of an implantation apparatus;

FIG. 2 is an enlarged, schematic view of the distal end of oneembodiment of an implantation apparatus described herein;

FIG. 3 is a perspective view of one embodiment of a handheldimplantation apparatus with the door opened and a needle assemblyinstalled therein;

FIG. 4 is a top view of the apparatus of FIG. 3 with front door removed;

FIG. 5 is an exploded view of the system for implanting a channelincluding the apparatus FIG. 3;

FIG. 6 is a perspective view of the distal end of the apparatus of FIG.3 with the needle assembly separated therefrom;

FIG. 7 is an enlarged perspective view of the needle assembly of FIG. 6;

FIG. 8 is an exploded view of the needle assembly of FIG. 7;

FIG. 9( a)-(f) are schematic views of the implantation apparatus of FIG.3 showing the plunger, guidewire and needle arms in different positionsduring the positioning and/or implantation steps as they correspond tothe positions of the plunger, guidewire, needle and channel within theeye;

FIG. 10 is a perspective view of another embodiment of an implantationapparatus with the needle assembly installed therein;

FIG. 11 is a perspective view of the implantation apparatus of FIG. 10and the disposable needle assembly in its extended state and separatedtherefrom;

FIG. 12 is a side view of another embodiment of a handheld and manuallyoperated implantation apparatus;

FIG. 13 is a side view of still another embodiment of a handheld andmanually operated implantation apparatus;

FIG. 14 is an enlarged side view of the needle assembly of the apparatusof FIG. 13;

FIG. 15 is a perspective view of a syringe type, manually operated,handheld implantation apparatus;

FIG. 16 is a schematic illustration of a method and apparatus for makinga gelatin microfistula channel in the form of a tube;

FIG. 17 is a schematic illustration an alternative embodiment of anapparatus for making a gelatin microfistula tube;

FIG. 18 is a perspective view of an apparatus for making a plurality ofmicrofistula gelatin tubes.

FIG. 19 is a front view of a graduated needle inserted into the eye of apatient;

FIG. 20 is a front view showing a transpupil channel insertion andplacement;

FIG. 21 is a schematic view showing an ipsilateral tangential channelinsertion and placement;

FIG. 22( a)-(d) depicts a series of steps showing an ipsilateral normalchannel insertion and placement using a U-shaped or otherwise arcuateneedle;

FIG. 23 is a perspective view of a U-shaped needle of the type shown inthe method of insertion and placement shown in FIGS. 22( a)-(d);

FIG. 24 is a front view of the U-shaped needle of FIG. 23;

FIG. 25 is a side view of a needle having a bend at its distal endportion including the guidewire and channel inserted therein;

FIG. 26 is a cross-sectional view of the needle, guidewire, plunger andchannel of the needle distal end portion of FIG. 25;

FIG. 27 is a side view of the needle, the plunger or guidewire of FIG.25, wherein a portion of the plunger or guidewire facilitates bending ofthe same;

FIG. 28 is a perspective view of a cylindrical channel including atapered end;

FIG. 29 is a perspective view of a cylindrical channel includingretaining tabs for limiting migration of the channel;

FIG. 30 is an end view of the tabbed channel of FIG. 29;

FIG. 31 is a perspective view of a cylindrical channel includingcentrally located barbs to limit migration of the implanted channel;

FIG. 32 is a perspective view of a cylindrical channel including barbslocated at one of the implanted channel to limit migration thereof;

FIG. 33 shows the tabbed channel of FIGS. 29-30 inserted within the eyeof the patient.

DESCRIPTION OF THE EMBODIMENTS

Methods and apparatus for delivering and implanting bioabsorbable tubesor shunts are generally disclosed in U.S. Pat. Nos. 6,544,249 and6,007,511, both of which have been previously incorporated by referencein their entireties. As set forth therein, and also with reference toFIG. 1, an implantation apparatus 10 is used to deliver and implant asmall micro-sized bioabsorbable tube i.e., the microfistula tube 26, toan area between the anterior chamber 16 and the sub-conjunctival space18 of the eye 12. The implanted microfistula tube 26 provides a channelthat continuously drains aqueous humor from anterior chamber 16 at adesired rate. Microfistula tube 26 remains implanted in the eye, andeventually dissolves.

FIG. 1 illustrates the distal (i.e., “working end”) end of the apparatus10 (including the microfistula tube 26) as it approaches the eye 12 asdescribed in U.S. Pat. No. 6,544,249. Unlike current trabeculectomyprocedures, in accordance with the method shown in FIG. 1, needle 22housing microfistula tube 26 approaches and enters the eye throughcornea 19 (ab interno) and not through the conjunctiva 14 (ab externo).This prevents damage to the conjunctiva, improves healing time andreduces the risk of complications that may result from other surgicaltechniques of the prior art (e.g., trabeculectomy). As further shown anddescribed in U.S. Pat. No. 6,544,249 and in FIG. 1, hollow needle 20 isintroduced through the cornea 19 and is advanced across the anteriorchamber 16 (as depicted by the broken line) in what is sometimesreferred to as a transpupil implant insertion. Channel 26 is eventuallyimplanted in the area spanning the sclera 21, anterior chamber 16 andthe sub-conjunctival space 18 (see also FIG. 8 of U.S. Pat. No.6,544,249). The methods, systems, apparatus and channels describedherein likewise utilize a hollow needle and a bioabsorbable channeldelivered by the needle ab interno through the cornea 19 or the surgicallimbus 17. As used herein, the term “channel” includes hollowmicrofistula tubes similar to the type generally described in U.S. Pat.No. 6,544,249 as well as other structures that include one or more flowpaths therethrough.

Turning now to a discussion of the methods, systems, apparatus andchannels that embody the present invention, as generally shown in FIG.2, the working end of implantation apparatus is provided as a needleassembly 20 that includes a hollow needle 22 defining an inner chamber23 and terminating in a sharpened tip. Placed within inner chamber 23 ofthe hollow needle 22 is a cylindrical inner tube or plunger 32 that iscoaxial with needle 22. In the loaded and ready to use condition,channel 26 is also placed or otherwise disposed within the hollowchamber 23 of needle 22 and is distally located relative to plunger 32.Both channel 26 and plunger 32 may be placed over and supported byoptional guidewire 28. As described in U.S. Pat. No. 6,544,249 and inthis disclosure, through relative movement of needle 22, plunger 32,guidewire 28, and channel 26 can be implanted into eye 12. As notedabove, guidewire 28 is optional and may be omitted where placement andadvancement of channel 26 does not require one.

As will be described in greater detail below, channel 26 may bedelivered to and implanted within the desired location of the eye in anyone of several different ways. The method of implantation (and system)may be fully automated, partially automated (and, thus, partiallymanual) or completely manual. For example, in a fully automatedprocedure, channel 26 may be delivered by robotic implantation whereby asurgeon controls the advancement of needle 22, plunger 32, optionalguidewire 28 and, as a result, channel 26 by remotely controlling arobot. In such fully automated, remotely controlled procedures, thesurgeon's hands typically do not contact implantation apparatus 10during the surgical procedure.

Alternatively, channel 26 may be delivered to the desired area of theeye with a “handheld” implantation apparatus, embodiments of which areshown in FIGS. 2-15 and described below. In one example of a handheldimplantation apparatus, discussed in more detail below, movement of thechannel 26, needle 22, and plunger 32 and optional guidewire 28 may becontrolled remotely by an operator using a microprocessor-based devicei.e., “controller,” while implantation apparatus 10 is physically heldby the surgeon. Insertion of the needle into the eye as well as certainrepositioning or adjusting steps may be performed manually by thesurgeon.

In the case of fully manual apparatus and methods, which are alsodiscussed below and shown in FIGS. 12-15, all of the positioning,repositioning, adjusting and implantation steps are performed manuallyby the surgeon.

One example of an implantation apparatus 10 and system embodying thepresent invention is shown in FIGS. 3-9. Although apparatus 10 shown inFIGS. 3-9 is preferably a handheld type implantation apparatus whererelative movement of the needle, optional guidewire and plunger isaccomplished automatically by pre-programmed instructions in amicroprocessor-based controller and at least some of the steps may bemanually performed by the surgeon, apparatus 10 can also be used in afully automated environment. In any event, implantation apparatus 10shown in FIG. 3 includes a reusable portion 30 and a disposable portionembodied in needle assembly 20. As will be discussed in greater detailbelow, needle assembly 20 is separately provided and is received by armsub-assembly 55 of implantation apparatus 30.

As shown in FIG. 3, implantation apparatus 10 includes a generallycylindrical body or housing 34, although as will be appreciated fromother embodiments disclosed herein, the body shape of housing 34 is notcritical. However, if apparatus 10 is to be held by the surgeon (i.e., ahandheld apparatus) the shape of housing 34 should be such that isergonomical, allowing for comfortable grasping by the surgeon. Housing34 is closed at its proximal end by end cap 38 and has an opening 39 atits distal end through which at least a portion of needle assembly 20extends. Door 36 provides access to the interior of housing 34 allowingfor easy insertion and removal of needle assembly 20. Locking means suchas slide lock 37 may be provided to secure door 36 to (and release door36 from) housing 34. Door 36 may be secured to housing 34 by a hinge 41allowing the door to swing open when it is unlocked. In an alternativeembodiment, door 36 may be slidably attached to housing 34 and access tothe interior of housing 34 may be achieved by sliding door 36 toward theproximal end of the housing 34. Of course, it will be appreciated thatother ways of providing access to the interior of the implantationapparatus 10 are also possible.

Housing 34 and door 36 may be made of any material that is suitable foruse in medical devices. For example, housing 34 may be made of alightweight aluminum or, more preferably, a biocompatible plasticmaterial. Examples of such suitable plastic materials includepolycarbonate and other polymeric resins such as Delrin® and Ultem®.Similarly, door 36 may be made of a plastic material such as theabove-described materials including polymers and polymer resins such aspolycarbonate, Delrin® and Ultem®. In a preferred embodiment, door maybe substantially translucent or transparent.

Re-usable portion 30 of implantation apparatus 10 houses the componentsrequired to effect movement of the needle assembly 20 components duringthe implantation procedure. As shown in FIGS. 3-6, implantationapparatus 10 houses a plurality of moveable arms, collectively referredto herein as the arm sub-assembly 55, which is adapted to receive needleassembly 20. Arms 54, 58 and 62 are axially moveable between theproximal and distal ends of apparatus 10 and are coupled to lead screws52(a)-(c) at their distal ends which, in turn, are coupled to one ormore drivers 44, 46, 48. In the embodiment shown in FIGS. 3-6, driversare preferably a plurality of gear or stepper motors 44, 46 and 48.Alternatively, arms may be driven pneumatically or otherwise.

With respect to the embodiments of FIGS. 3-6, motors 44, 46 and 48 arehoused near the proximal end of implantation apparatus 10. Motors 44, 46and 48 may be stacked or bundled in parallel in the manner shown in FIG.5 and held in place by front motor mount 50 and rear motor mount 40.

As indicated above, each of the motors 44, 46 and 48 (or other drivers)is coupled to one of the lead screws 52(a)-(c), which, in turn, arecoupled to movable arms 54, 58 and 62 of arm sub-assembly 55. Forexample, with specific reference to the embodiment of FIGS. 3-6, leadscrew 50(a) is coupled to guidewire arm 54; lead screw 50(b) is coupledto plunger arm 58; and lead screw 50(c) is coupled to needle arm 62.Motors 44, 46 and 48 may be selectively and independently activated byswitches on the apparatus 10 itself or as schematically shown in FIG. 5as described, may be coupled to a remote controller 8 of the system. Inone embodiment, apparatus 10 includes printed circuit board 7 whichestablishes an electrical connection between motors 44, 46 and 48 andcontroller 8. Controller 8 may include a control box that supplies powerand pre-programmed positioning instructions to the implantationapparatus 30 generally and motors 44, 46 and 48, specifically. Movementsof the various arms 54, 58 and 62 can be initiated by the surgeon via afoot switch or other type of remote control 6.

As shown in the Figures, arms 54, 58 and 62 are preferably of varyingaxial lengths. Each of the arms 54, 58 and 62 includes a slot forreceiving a portion of the needle assembly 20 (described below.) Thus,guidewire arm 54 includes a guidewire hub slot 57; plunger arm 58includes a plunger hub slot 59 and needle arm 62 includes a needle hubslot 63.

In a preferred embodiment, each of the arms 54, 58 and 62 includes atits distal and/or proximal ends a portion having an enlargedcross-section. The distal “blocks” 54(a), 58(a) and 62(a) provideabutment surfaces which limit axial movement of the respective arms. Aswill be seen from the discussion of the implantation method, the distalblocks which also define slots 59, 62 and 63 limit movement of theparticular arms, thereby ensuring that the guidewire, plunger andchannel 26 do not move beyond a pre-determined distance. Similarly, wall65 of housing 34 limits movement of needle arm 62, likewise ensuringthat the needle does not penetrate the eye beyond a desired distance.Proximal blocks 58(a), 58(b) and 58(c) (not shown) likewise provide anabutment surfaces for contacting fixed collars 53 on lead screws52(a)-(c). Contact between the surfaces of blocks 58(a), 58(b) and 58(c)and respective collars 53 provides an indication that arms of armsubassembly 55 are in their rearmost or “hard stop” position, discussedbelow. Blocks 58(a)-(c) also include internal threaded nuts throughwhich lead screws 50(a)-(c) travel.

As further seen in FIGS. 3-6, implantation apparatus 10 includes a guideblock 66 attached to needle arm 62. Guide block 66 defines two partiallyenclosed apertures for slidably retaining guidewire arm 54 and plungerarm 58. Guide block 66 prevents rotation or other undesired dislocationof guidewire arm 54 and plunger arm 58 and maintains these components inan axially aligned orientation. Guide block 66 also serves as a stopthat limits movement of arms 54 and 58.

As noted above, arm sub-assembly 55 is adapted to receive needleassembly 20. Needle assembly, shown in FIGS. 7 and 8 is itself made of aplurality of separate, and co-axially assembled parts. Co-axial assemblyof these constituent parts allows for relative axial movement ofoptional guidewire 28, needle 20 and plunger 32. As shown in FIGS. 7 and8, in one embodiment, needle assembly includes a guidewire hub 72. Inthe embodiment shown, guidewire hub 72 includes a distal cylinder 82 anda proximal block 84. Guidewire 28 extends from the cylinder 82 and isreceived within plunger hub 68 which likewise includes a distal hollowcylinder and proximal block 90. Plunger tube 32 extends from plungercylinder 88 and when brought together with guidewire hub 72 surroundsguidewire 86 along most of its length. Both guidewire 28 and plungertube 92 are then received by needle hub 96. A hollow needle 22 attachedto needle mount 23 is mounted on needle hub 96. Hollow needle 22 has aninner diameter sufficient to receive the assembled co-axial guidewire 86and plunger 92. Of course, it will be appreciated that in certainembodiments, a guidewire may not be required and that needle assembly 20may include a plunger and needle only.

As best shown in FIG. 6, needle assembly 20 is adapted for placementwithin arm assembly 55. More specifically, guidewire block 84, plungerblock 90 and needle block 94 of needle assembly 20 are received by theslots 57, 59 and 63, respectively, of arm sub-assembly 55. Each ofblocks 84, 90 and 94 may include an upstanding pin 85, 91 and 95(respectively). Pins 85, 91 and 95 are of a height sufficient so as toalmost contact the inner surface of door 36 (when closed). Providingpins of sufficient height keeps needle assembly from becoming dislodgedfrom sub-assembly 55 in the event that apparatus 10 is rotated by thesurgeon. As shown in FIGS. 7 and 8, hollow needle 22 is preferablyprotected prior to use by removable needle cap 80.

Another embodiment of a handheld implantation apparatus is shown inFIGS. 10-11. As in the embodiment described above, hand-heldimplantation apparatus 10 of FIG. 10 includes a reusable portion 30 thatincludes handle 180, movable block 182 and slider assembly 214. As withthe embodiment of FIGS. 3-9 above, needle assembly 20, itself includesseveral different components that can be preassembled (as shown in FIG.10) and are axially movable relative to one another. For example, in theembodiment shown in FIG. 10, needle assembly 20 includes plunger 32,needle adapter 184 and guidewire holder 24. Plunger 32 has a hollowcylindrical body which has an open distal end and an open proximal end.Open proximal end of plunger 32 receives guidewire 28 and guidewireholder 24.

As further shown in FIG. 10, distal end of plunger 32 is received byhollow needle adapter 184 and needle adapter 184 receives disposableneedle 22. Needle 22 includes a distal piercing end and a hub 188 whichis fitted over needle adapter 184. Once assembled, guidewire extendsfrom guidewire holder 24 through plunger 32, through needle adapter 184and needle 22. In the embodiments of FIG. 10, channel 26 is typicallyplaced on guidewire 28 near the distal end thereof within hollow needle22.

Needle assembly 20 is mounted onto reusable handheld portion 30. Moreparticularly, as shown in FIG. 3, needle assembly is fitted into slots192, 194 and 196 of implantation apparatus 30. For example, collar 198of guidewire holder 24 is received within slot 192, collar 200 ofintermediate tube 32 is positioned within slot 194, and collar 202 ofneedle adapter 34 is received within slot 196.

Implantation apparatus 10 includes a handle 180. Handle 180 preferablyincludes groove 206 along the side wall for easy gripping by thesurgeon. As shown in FIGS. 10 and 11, handle 204 supports movable sliderblock 182. Block 182 includes a slide 210 that fits within a centralslot of handle 180. During use of implantation apparatus 10, block 182may move axially within the slot of handle 180. Movable slider block 182may also include a slot 212 (see FIG. 10) which receives plunger blockassembly 214. As shown in the figures, plunger block 214 may be slidablewithin block 182. Plunger block assembly 214 includes forwardlyextending arms 216 which defines at its distal end a slot 192 (in whichcollar 25 of guidewire holder 24 is received). Plunger block assemblyalso includes guidewire slider block 218 that is movable within slot 219defined by arms 216. Guidewire slider block 218 is coupled to motor 230(discussed below) by screw 220.

Reusable portion 30 of handheld implantation apparatus 10 generallydepicted in FIGS. 10 and 11 may further include drivers for selectivelyactuating movement of the component parts of needle assembly 20, such asneedle 22, guidewire 28, plunger 32, and channel 26. As in theembodiment of FIGS. 3-9, in the embodiment of FIGS. 10 and 11, thedrivers for selectively moving these and other components may be one ormore motors, such as gear or stepper motors. Motors 230 may beselectively activated to move the desired component of apparatus 10. Inone non-limiting example shown in FIGS. 10 and 11, a plurality ofstepper motors 230(a), (b) and (c) are carried by handheld implantationapparatus. Motors 230(a)-(c) may be selectively activated by switches onthe apparatus itself, remote hand-operated switches, a foot-operatedcontroller and/or an automatically controlled via a preprogrammedcontroller (i.e., computer) 8.

Regardless of the means of control, in the example shown in FIGS. 10 and11, motor 230(a) causes movement of guidewire slider block 218. Movementof guidewire slider block 218 which holds collar 25 of guidewire holder24 results in selective back and forth movement of guidewire 28. Motor230(b) moves arm 216 within slot 212 which holds collar 200 of plunger32, allowing for back and forth movement of plunger 32. Finally, motor230(c) drives block 182 including the entire needle assembly 20 furtherincluding block 214 and its associated components.

Of course, as described in relation to the embodiment of FIGS. 10-11,means for advancing or moving the operative components of handheldimplantation apparatus 30 of FIGS. 11-12 need not be electrical and/ormotor driven. Other embodiments of a handheld apparatus 10 that includeother ways for actuating movement of the individual components may alsobe employed. For example, as shown in FIGS. 12-15, in alternativeembodiments of a handheld implantation apparatus, the apparatus 10 mayinclude mechanical means for selectively advancing the component partsof the needle assembly and the handheld implantation apparatus.

Turning to FIG. 12, implantation apparatus 110 includes a reusablehandheld portion 112 that receives a disposable needle assembly 114.Implantation apparatus 110 includes a thumbwheel 116 placed on andmovable along threaded screw 118. Attached to thumbwheel 116 is asyringe body 120. Distal end of syringe 120 receives needle assembly122. Implantation apparatus 110 includes a conduit that extends throughthe handle 113 and is adapted for receiving guidewire 28.

Placement of channel 26 onto guidewire 28 may be achieved by turningthumbwheel 116 in a first direction to retract needle assembly 122 andhollow needle 124, thereby revealing the distal end of guidewire 28 andplunger tube 32. At that point, channel 26 is placed (typicallymanually) on guidewire 28 so that the proximal end thereof (the endopposite the leading end of channel 26) of channel comes into contactwith the distal end of plunger 32. Thumbwheel 116 is then turned in anopposite direction to the first direction to slide needle 124 overplunger tube 32 and channel 26.

Channel 26 is now ready for implantation. During the implantationprocess, needle 124 is inserted into the eye and, more specifically, thecornea 19 or surgical limbus 17 of the eye in the manner described aboveand in U.S. Pat. No. 6,544,249. Needle 124 is advanced across anteriorchamber 16 and into the sub-conjunctival space 18, stopping short of theconjunctiva 14. Thumbwheel 116 is then rotated again in the firstdirection to retract needle 124 and thereby expose channel 26. Once inplace, guidewire is retracted, releasing microfistula 26 from guidewire28. Retraction of guidewire may be achieved manually by a simple pullingof guidewire 28 at the proximal end of apparatus 110. Once channel 26 isin its final position, needle 124 is removed.

FIGS. 13 and 14 illustrate another embodiment of a handheld implantationapparatus 130 that likewise utilizes mechanical means for advancingand/or selectively moving the component parts of the needle assemblyand/or apparatus 130. As in the embodiment of FIG. 12, handheldimplantation apparatus relies on mechanically driving the componentparts. As shown in FIG. 13, implantation apparatus 130 includes handleportion 132 with a needle assembly 134 attached to the distal end ofbody 132. A thumbwheel 136 is rotatable and coupled to an internal screw(not shown). Internal screw is attached to arms 138 which grasp flange140 of needle assembly 134, such that turning of thumbscrew 136 effectsaxial movement of needle assembly 134.

In contrast to the embodiment of FIG. 12, implantation apparatus 130 mayfurther include additional means for controlling movement of othercomponents of the implantation apparatus. For example, in the embodimentof FIG. 13, a second thumbwheel 142 is mechanically coupled to guidewire28. A rotation of thumbwheel 142 allows for retraction of guidewire 28after implantation of channel 28.

FIG. 14 provides an enlarged view of needle assembly 134 shown in FIG.13. As seen in FIG. 14, an assembly retainer 146 is provided. Assemblyretainer 146 is affixed to the needle assembly 134 during shipment toprevent movement of guidewire 28 and control tube. Retainer is removedprior to insertion of the needle assembly 134 onto the handle 132 ofapparatus 130.

FIG. 15 shows another embodiment of an implantation apparatus. Theimplantation apparatus 150 of FIG. 8 includes a handle 152, a movable orslidable syringe portion 154 and a trigger 156 for actuating movement ofslidable syringe 124. Implantation apparatus 150 further includes anattachable needle assembly 158 (with needle 22) at the distal end ofsyringe 154. As shown in FIG. 15, guidewire 28 extends throughimplantation apparatus 150 in similar fashion to the apparatus of FIG.12. Guidewire 28 extends through barrel 154 and carries a tube 32 nearits distal end. Barrel 154 is preferably filed with gas (e.g., air, CO₂,nitrogen or liquid (e.g., water, trypan blue, saline or a viscoelasticsolution).

For placement of channel 26 onto guidewire 28, trigger 156 is pulled,resulting in rearward movement of syringe 154 and needle 22. Rearwardmovement of needle 22 exposes guidewire 28 and allows for placement ofchannel 26 onto guidewire. Release of the trigger 158 advances needle 22to cover guidewire 28 and channel 26. As in the previous embodiments,needle 22 pierces cornea 19 or surgical limbus 17, and is advancedthrough anterior chamber 16 to the desired location of the eye (i.e. thearea between the sub-conjunctival space 18 and the anterior chamber).Trigger 156 is once again pulled to move needle assembly 158 in arearward direction thereby exposing channel 26 carried by guidewire 28.Once the surgeon has determined that the channel 26 is in the desiredlocation, guidewire 28 is retracted, thereby releasing channel 26. Asshown in FIG. 15, retraction of guidewire 28 may be performed manually,as in the embodiment of FIG. 12, by simply pulling guidewire 28.Alternatively, mechanical means for moving guidewire, as in the examplesof FIGS. 12 and 13, may also be provided.

Although selective movement of guidewire 28, needle assembly, plunger 32or guidewire holder 24 with the channel 26 using electrical, mechanicalor even some manual means have been described, other means for actuatingmovement of these components may also be used instead of or in additionto such means. For example, movement of the various component parts maybe achieved by pneumatic control or fluidic control.

The method of implanting channel 26 using implantation apparatus willnow be described. The method will be described with particular referenceto the embodiment of FIGS. 3-9, although many of the steps described mayalso be employed using other embodiments of the implantation apparatus.In addition, depending on the type of apparatus and type of channelused, there may be variations to some of the method steps. For example,in some embodiments, a guidewire may be omitted. In addition, theadvancement and retraction steps of the parts of needle assembly may becontinuous or incremental. Regardless of the apparatus used, thesequence of steps, distances traveled and continuous or incrementalmovement, the ultimate location of channel 26 is substantially the sameusing any of the methods, systems and apparatus described herein.

At the outset, it will be appreciated that the implantation of channel26 requires precise placement of the channel 26 in the correct locationwithin the eye. Moreover, it will also be appreciated that the distancestraveled by the channel 26, plunger 32, guidewire 28 and needle 22 aretypically measured in millimeters. Such precision may be difficult foreven the most skilled surgeon to achieve by manual manipulation (due tonatural hand tremors in humans). Accordingly, in embodiments other thanthe manual hand-held implanters in FIGS. 12-15, many of the actualimplantation steps are preferably carried out under the automaticcontrol of an external, preprogrammed controller 8. While the initialeye entry steps and some repositioning steps may be performed manuallyby the surgeon, steps related to the release and location of channel 26may be automatically controlled.

In a first step, preferably performed during factory assembly, channel26 is loaded into needle assembly 20. During loading, the distal tip ofguidewire preferably extends slightly beyond the beveled tip of hollowneedle 22. Channel 26 may be manually placed on guidewire 28 untilproximal end of channel 26 contacts the distal end of plunger 32.Guidewire 28, with channel 26 placed thereon is then retracted intohollow needle 22.

Prior to loading needle assembly 20 into apparatus 30, pre-positioningof arm-subassembly may be desired or required. Thus, in a first step,all motors are activated to retract guidewire arm 54, plunger arm 58 andneedle arm 62 to a proximal most position such that the proximal endsurfaces of the arms abut against collars 53. This “hard stop” positionis shown schematically in FIG. 9 a. The operator may then prepareimplantation apparatus 30 for loading of needle assembly by activatingeach motor and advancing each arm assembly 55 to a “home” position andshown in FIG. 9( b). As will be seen in FIG. 9( b) movement of needlearm 62 is restricted by wall 70 of apparatus 30. With the motorsproperly aligned in the “home” position, needle assembly is installed byinserting guidewire hub block 86 into guidewire hub slot 57; plunger hubblock 90 into plunger hub slot 59 and needle hub block into slot 63.With needle assembly 20 properly installed, the surgeon may begin theprocedure by inserting the end distal tip of hollow needle 22 into theeye. As shown in FIG. 1 and as previously described, the surgeon insertsthe hollow needle 22 into the anterior chamber via the cornea orsurgical limbus of the eye and advances it either manually (or underautomatic control) to a location short of the final implantation site.Alternatively, the surgeon may first make an incision in the eye andinsert needle 22 through the incision. Once the needle 22 has beenproperly inserted and placed, the program may be activated to commenceautomatic implantation of channel 26. In a first implantation step,simultaneously motors) 44 and 46 are activated to advance guidewire arm54 and plunger are 58 as shown in FIG. 9( c) which thereby advanceschannel 26 forward into the subconjunctival space of the eye, asgenerally depicted in FIG. 9( c). For example, in one embodiment,plunger 32 and guidewire 28 are advanced approximately a total of 2millimeters. Preferably, the rate of placement of channel is carefullycontrolled because it allows the channel to absorb fluid from thesurrounding tissue thereby causing it to swell and to provide betteranchoring in the tissue. Rapid advancement or placement of microfistulachannel 26 may not allow tube 26 to adequately swell which can possiblyresult in unwanted migration of channel 26 after implantation. In oneembodiment, the rate of placement may be between approximately 0.25-0.65mm/sec.

After the advancement of the plunger and guidewire described above,motor 48 is activated and needle arm 62 is moved in a rearward directionsuch that needle 22 is withdrawn from its position shown in FIG. 9( c)to the position shown in FIG. 9( d). Withdrawal of needle 22 shouldpreferably expose the entire length of channel 26, and, in addition, thedistal end of the plunger, thereby allowing the surgeon to visualize thefinal position of the proximal edge of the channel. In one embodiment,the distance that hollow needle 22 is withdrawn is approximately 4.2millimeters. At this point, the program prompts (e.g., audibly) thesurgeon to visually view the location of channel 26 and determine if itis correctly placed. The surgeon can manually make any adjustments to adesired position by moving the implanter forward or backward. Theautomatic system may be programmed to allow the surgeon sufficient timeto make any further manual adjustments and may require the surgeon topress the foot or other switch or otherwise effect movement to continuedelivery of the channel. After a selected period of time, the automatedprogram preferably resumes control of implantation procedure byactivating motor guidewire motor 44, to retract guidewire arm 54 andthus withdraw guidewire 28 as shown in FIG. 9( e). Removal of theguidewire preferably occurs in one single step as shown in FIG. 9( e).Finally, the system will then preferably alert the surgeon that theprocedure is now complete and the needle 22 may be withdrawn (manuallyor automatically) from the eye as shown in FIG. 9( f).

From the preceding discussion, it will be appreciated that bioabsorbablemicrofistula channel is implanted by directing the needle across theanterior chamber, entering the trabecular meshwork (preferably betweenSchwalbe's Line and the Scleral spur), and directing the needle throughthe sclera until the distal tip of the needle is visible in thesubconjunctival space. The length of the channel through the sclerashould be approximately 2-4 mm. Once the surgeon has placed the needlein this location, he may actuate the implanter to begin the releasesteps. The channel is released and the needle is withdrawn such thatapproximately 1-2 mm of the channel resides in the sub conjunctivalspace, approximately 2-4 mm resides in the scleral channel, andapproximately 1-2 mm resides in the anterior chamber. Once the channelis released, the surgeon removes apparatus needle 20.

Proper positioning of the bioabsorbable channel 26 should be carefullycontrolled for at least the following reasons. If the surgical procedureresults in the formation of a bleb, the more posterior the bleb islocated, the fewer complications can be expected. Additionally, the blebinterferes less with eyelid motion and is generally more comfortable forthe patient. Second, a longer scleral channel provides more surfacecontact between the channel and the tissue providing better anchoring.Third, the location of the channel may play a role in stimulating theformation of active drainage structures such as veins or lymph vessels.Finally, the location of the channel should be such so as to avoid otheranatomical structures such as the ciliary body, iris, and cornea. Traumato these structures could cause bleeding and other complications for thepatient. Additionally, if the bleb is shallow in height and diffuse insurface area, it provides better drainage and less mechanicalinterference with the patient's eye. Tall, anteriorly located blebs aremore susceptible to complications such as conjunctival erosions orblebitis which require further intervention by the surgeon.

The ab interno approach provides better placement than the ab externoapproach because it provides the surgeon better visibility for enteringthe eye. If directing the needle from an ab externo approach, it isoften very difficult for the surgeon to direct the needle to thetrabecular meshwork (between Schwalbe's line and the scleral spur)without damaging the cornea, iris, or ciliary body.

In an alternative method of implantation, it is possible to direct theneedle from the trabecular meshwork into the suprachoroidal space(instead of the subconjunctival space) and provide pressure relief byconnecting these two spaces. The suprachoroidal space also calledsupracilliary space has been shown to be at a pressure of a few mmHgbelow the pressure in the anterior chamber.

Common to all of the embodiments of handheld implantation apparatus area needle assembly including a hollow needle. In a preferred embodiment,hollow needle 22 may be any needle suitable for use in medicalprocedures. As such, needle 22 is made of a hard and rigid material suchas stainless steel with a beveled sharpened distal tip. Needle 22 isbonded, welded, overmolded, or otherwise attached to the needle mount 23and/or hub that is adapted for placement onto the distal end of a needleassembly. The needle 22 is disposable and intended for one time use.

Hollow needle 22 and indeed, the entire needle assembly may besterilized by known sterilization techniques such as autoclaving,ethylene oxide, plasma, electron beam, or gamma radiation sterilization.In a preferred embodiment, needle 22 is a 25 gauge thin walled needlethat is commercially available from Terumo Medical Corp., Elkton, Md.21921. The inside diameter of hollow needle 22 must be sufficient toaccommodate optional guidewire 28, channel 26 and plunger tube 32, withan inner diameter of 200-400 um being preferred. The usable length ofneedle 22 may be anywhere between 20-30 mm, although a length ofapproximately 22 mm is typical and preferred. Preferably, needle 22 mayinclude markings or graduations 27 near the distal tip as shown in FIG.19. A graduated needle may be particularly useful to a surgeon inasmuchas much of the needle within the eye is not visible to the surgeon.Typically, the only visible portion of needle 22 is the portion withinthe anterior chamber. Accordingly, graduations 27 uniformly spaced alongthe needle shaft assist the surgeon in determining how far to advancethe needle in order to place channel 26 in the desired location. In oneembodiment, the graduations may be applied using laser marks, ink, paintor engraving and are typically spaced 0.1 to 1.0 mm apart.

While a straight hollow needle of the type typically used in medialprocedures is generally preferred, in an alternative to the needle shownin the FIGS. 3-15 and described above, needle 22 may be rigid and have adistal portion that is arcuate as shown in FIGS. 22-24. As shown inFIGS. 22( a)-(d) and FIGS. 23-24 arcuate needle may be preferablyU-shaped or substantially U-shaped. With an “arcuate” needle, instead ofpushing the needle into the patient's eye, the surgeon may orient theneedle to “pull” the needle into the patient's eye. As shown in FIGS.23-24, the distal portion of the needle 22 terminating in the beveledtip, identified by reference number 96 is preferably disposed obliquelyrelative to the longitudinal axis of needle shaft 98 as seen in FIG. 24.

Providing a piercing end 96 that is bent away from the plane of needleshaft 98 can facilitate manipulation and rotation of needle 22 duringimplantation of tube 26. It may also provide the surgeon with greaterflexibility in terms of selecting the corneal entry site and theultimate final position of channel 26. This is perhaps best seen withreference to FIGS. 20, 21 and 22(a)-(d).

For example, FIG. 20 depicts a transpupil implantation deliverygenerally described in U.S. Pat. No. 6,544,249 as shown in FIG. 1. Whilethe approach is satisfactory, it does require the needle to cross thevisual axis. In the event of a surgical error that causes damage to thecornea or lens, corrective surgery may be required.

FIG. 21 depicts an alternative method of delivery referred to as anipsilateral tangential delivery of channel 26. In the ipsilateraltangential delivery method, the straight needle is directed tangentiallyto the pupil 100 border and the surgical limbus. This type of implantdelivery allows the channel to be delivered to a greater circumferenceof the eye and has the advantage of avoiding the visual axis. Avoidingthe visual axis reduces the risk of complications to the cornea 19 andlens through contact during surgery. Ipsilateral tangential delivery isa modification of the transpupil implant location generally described inU.S. Pat. No. 6,544,249, previously incorporated by reference.

Although the transpupil implant delivery and/or the ipsilateraltangential delivery, if performed correctly, are acceptable methods ofdelivering channel 26, they do somewhat limit the location of thecorneal entry site due to interference with the nose and eye orbitbones. In that regard, an arcuate needle of the type described above andshown in FIGS. 22( a)-(d) and FIGS. 23-24 may provide greaterflexibility to the surgeon. With an arcuate needle, channel 26 may beplaced anywhere around the 360° circumference of the eye, including thetemporal quadrants which would not be otherwise accessible for thereasons discussed above.

A further advantage of the arcuate needle and the delivery implantmethod associated therewith is that microfistula channel 26 can bedelivered without crossing the lens i.e., visual axis, thereby reducingthe risk of complications. An arcuate needle design may also allow thesurgery to be done in patients with abnormal anatomy or who havepreviously undergone surgery.

In accordance with delivering a microfistula channel 26 using theU-shaped hollow needle 20 of FIGS. 23 and 24, as noted above, instead ofpushing the needle into the patient's eye, the surgeon orients theneedle to “pull” needle 22 into the patient's eye. Thus, as shown inFIG. 22( a), the pointed tip of hollow needle 22 is inserted at thedesired corneal entry point and pulled in the direction of the arrow.Once the portion of needle 22 that contains the channel 26 is in thepatient's eye, the surgeon rotates the needle and directs the needle 22toward the target within the angle of the anterior chamber. Afteradjusting needle 22 to the proper position, the surgeon again pulls theneedle 22 in the direction of the arrow of FIG. 22( b) so that theneedle is directed through the trabecular mesh work and sclera. Theparticular advancement and delivery steps described previously are thenperformed to place the channel 26 in the desired location and withdrawthe guidewire plunger and needle from the eye. Of course, retraction andother movements of the needle may be automatically controlled in themanner described above and as shown in FIG. 9.

In a further embodiment, a hollow needle 22 that is bent (but notnecessarily in a U-shape as described above), may be provided. A needleof this type is shown in FIGS. 25-27. As with the “arcuate” or U-shapedneedles discussed above, a simple bend in the distal portion of needle22 can likewise avoid interference from the patient's facial features. Abend that creates an angle α of between 90°-180° may be preferred.Providing a needle 22 with a bend is also ergonomically desirable inthat it improves the position of the surgeon's hands during surgery. Forexample, by providing a bend in the distal portion of needle 22, asurgeon may rest and stabilize his hands on the patient's forehead orother support while making the initial corneal entry and carrying outthe later implantation steps. Providing a bend in the distal portion ofneedle 22 is not merely an alternative to the U-shaped needle of FIGS.23 and 24. In fact, both features i.e., a needle with an arcuate distalportion and further having a bend near the distal tip may be employedtogether in the needle 22.

Whether the needle is U-shaped or bent at an angle α shown in FIG. 25,the component parts of needle 22 must likewise be susceptible tobending. Accordingly, instead of a rigid plunger 32 and guidewire 28,both the plunger and guidewire may be, in part, bendable or be made of amaterial that is bendable, yet provides adequate support and hasadequate strength. In one example, the plunger 32 may be made of atightly wound coil such as but limited to a spring or coil.Alternatively, at least a portion of guidewire 28 or plunger 32 may bemade of a flexible plastic material including a polymeric material,examples of which include polyimide, PEEK, Pebax or Teflon. Otherbendable, flexible materials may also be used. Similarly, guidewire 28may be made of any of the above-described materials or a material suchas nitinol which has shape memory characteristics. The entire plunger orguidewire 28 may be made of the flexible materials described above or,as shown in FIG. 27 only a portion of the guidewire 28 or plunger tube32 may be made of the selected material or be otherwise bendable.

Typically, however, guidewire 28 is preferably a narrow gauge wire madeof a suitable rigid material. A preferred material is tungsten orstainless steel, although other non-metallic materials may also be used.In a preferred embodiment, guidewire 28 is solid with an outsidediameter of approximately 50-200 (ideally 125) microns. Where guidewire28 is made of tungsten, it may be coated with a Teflon, polymeric, orother plastic material to reduce friction and assist in movement ofchannel 26 along guidewire 28 during implantation.

Channels 26 useful in the present invention, are preferably made of abiocompatible and preferably bioabsorbable material. The materialspreferably have a selected rigidity, a selected stiffness and a selectedability to swell (during manufacture and/or after implantation) in orderto provide for secure implantation of the channel in the desired sectionof the eye. Selecting a material that is capable of a controlledswelling is also desirable. By controlled swelling, it is meant that theswellable material is such that the outer diameter of the channelexpands (increases) without decreasing the inner diameter. The innerdiameter may increase or remain substantially the same. The materialsand methods for making channels described below provide such controlledswelling. By sufficient biocompatibility, it is meant that the materialselected should be one that avoids moderate to severe inflammatory orimmune reactions or scarring in the eye. The bioabsorbability is suchthat the channel is capable of being absorbed by the body after it hasbeen implanted for a period of anywhere between 30 days and 2 years and,more preferably, several months such as 4-7 months.

In one embodiment, the material selected for the channels is preferablya gelatin or other similar material. In a preferred embodiment, thegelatin used for making the channel is known as gelatin Type B frombovine skin. A preferred gelatin is PB Leiner gelatin from bovine skin,Type B, 225 Bloom, USP. Another material that may be used in the makingof the channels is a gelatin Type A from porcine skin also availablefrom Sigma Chemical. Such gelatin is available is available from SigmaChemical Company of St. Louis, Mo. under Code G-9382. Still othersuitable gelatins include bovine bone gelatin, porcine bone gelatin andhuman-derived gelatins. In addition to gelatins, microfistula channelmay be made of hydroxypropyl methycellulose (HPMC), collagen, polylacticacid, polyglycolic acid, hyaluronic acid and glycosaminoglycans.

In accordance with the present invention, gelatin channels arepreferably cross-linked. Cross-linking increases the inter- andintramolecular binding of the gelatin substrate. Any means forcross-linking the gelatin may be used. In a preferred embodiment, theformed gelatin channels are treated with a solution of a cross-linkingagent such as, but not limited to, glutaraldehyde. Other suitablecompounds for cross-linking include1-ethyl-3[3-(dimethyamino)propyl]carbodiimide (EDC). Cross-linking byradiation, such as gamma or electron beam (e-beam) may be alternativelyemployed.

In one embodiment, the gelatin channels are contacted with a solution ofapproximately 25% glutaraldehyde for a selected period of time. Onesuitable form of glutaraldehyde is a grade 1 G5882 glutaraldehydeavailable from Sigma Aldridge Company of Germany, although otherglutaraldehyde solutions may also be used. The pH of the glutaraldehydesolution should preferably be in the range of 7 to 7.8 and, morepreferably, 7.35-7.44 and typically approximately 7.4±0.01. Ifnecessary, the pH may be adjusted by adding a suitable amount of a basesuch as sodium hydroxide as needed.

Channels used in the present invention are generally cylindricallyshaped having an outside cylindrical wall and, in one embodiment, ahollow interior. The channels preferably have an inside diameter ofapproximately 50-250 microns and, more preferably, an inside diameterand us, a flow path diameter of approximately 150 to 230 microns. Theoutside diameter of the channels may be approximately 190-300 with aminimum wall thickness of 30-70 microns for stiffness.

As shown in FIG. 28, one end of tube 26 may be slightly tapered to limitor prevent migration of tube 26 after it has been implanted. Other meansfor limiting migration are also shown in FIGS. 29-33. For example,channel 26 may include expandable tab 150 along outer surface 152 oftube 26. As shown in FIG. 29, prior to deployment and introduction oftube into the patient's eye, tabs 150 are rolled or otherwise pressedagainst surface 152. Tabs 150 may also be features that are cut out ofthe outer surface of channel 26 (i.e., not separately applied). Uponcontact with an aqueous environment, tabs 150 are deployed.Specifically, contact with an aqueous environment causes tabs 150 toexpand as shown in FIG. 30 and, thereby, create an obstruction whichlimits or prevents migration of tube 26. Tube 26 may include a pluralityof tabs, typically but not limited to 1-4, and may be located nearer thesubconjuctival side, the anterior chamber or both, as shown in FIG. 33.Other means for limiting or preventing migration include barbs 158placed along the length of tube 26 as shown in FIGS. 31-32 and alsodisclosed in U.S. Pat. Nos. 6,544,249 and 6,007,511, previouslyincorporated by reference.

The length of the channel may be any length sufficient to provide apassageway or canal between the anterior chamber and the subconjunctivalspace. Typically, the length of the channel is between approximately 2to 8 millimeters with a total length of approximately 6 millimeters, inmost cases being preferred. The inner diameter and/or length of tube 26can be varied in order to regulate the flow rate through channel 26. Apreferred flow rate is approximately 1-3 microliters per minute, with aflow rate of approximately 2 microliters being more preferred.

In one embodiment, channels 26 may be made by dipping a core orsubstrate such as a wire of a suitable diameter in a solution ofgelatin. The gelatin solution is typically prepared by dissolving agelatin powder in de-ionized water or sterile water for injection andplacing the dissolved gelatin in a water bath at a temperature ofapproximately 55° C. with thorough mixing to ensure complete dissolutionof the gelatin. In one embodiment, the ratio of solid gelatin to wateris approximately 10% to 50% gelatin by weight to 50% to 90% by weight ofwater. In an embodiment, the gelatin solution includes approximately 40%by weight, gelatin dissolved in water. The resulting gelatin solutionpreferably is devoid of any air bubbles and has a viscosity that isbetween approximately 200-500 cp and more preferably betweenapproximately 260 and 410 cp (centipoise).

Once the gelatin solution has been prepared, in accordance with themethod described above, supporting structures such as wires having aselected diameter are dipped into the solution to form the gelatinchannels. Stainless steel wires coated with a biocompatible, lubriciousmaterial such as polytetrafluoroethylene (Teflon) are preferred.

Typically, the wires are gently lowered into a container of the gelatinsolution and then slowly withdrawn. The rate of movement is selected tocontrol the thickness of the coat. In addition, it is preferred that athe tube be removed at a constant rate in order to provide the desiredcoating. To ensure that the gelatin is spread evenly over the surface ofthe wire, in one embodiment, the wires may be rotated in a stream ofcool air which helps to set the gelatin solution and affix film onto thewire. Dipping and withdrawing the wire supports may be repeated severaltimes to further ensure even coating of the gelatin. Once the wires havebeen sufficiently coated with gelatin, the resulting gelatin films onthe wire may be dried at room temperature for at least 1 hour, and morepreferably, approximately 10 to 24 hours. Apparatus for forming gelatintubes are described below.

Once dried, the formed microfistula gelatin channels are treated with across-linking agent. In one embodiment, the formed microfistula gelatinfilms may be cross-linked by dipping the wire (with film thereon) intothe 25% glutaraldehyde solution, at pH of approximately 7.0-7.8 and morepreferably approximately 7.35-7.44 at room temperature for at least 4hours and preferably between approximately 10 to 36 hours, depending onthe degree of cross-linking desired. In one embodiment, formed channelis contacted with a cross-linking agent such as gluteraldehyde for atleast approximately 16 hours. Cross-linking can also be accelerated whenit is performed a high temperatures. It is believed that the degree ofcross-linking is proportional to the bioabsorption time of the channelonce implanted. In general, the more cross-linking, the longer thesurvival of the channel in the body.

The residual glutaraldehyde or other cross-linking agent is removed fromthe formed channels by soaking the tubes in a volume of sterile waterfor injection. The water may optionally be replaced at regularintervals, circulated or re-circulated to accelerate diffusion of theunbound glutaraldehyde from the tube. The tubes are washed for a periodof a few hours to a period of a few months with the ideal time being3-14 days. The now cross-linked gelatin tubes may then be dried (cured)at ambient temperature for a selected period of time. It has beenobserved that a drying period of approximately 48-96 hours and moretypically 3 days (i.e., 72 hours) may be preferred for the formation ofthe cross-linked gelatin tubes.

Where a cross-linking agent is used, it may be desirable to include aquenching agent in the method of making channel 26. Quenching agentsremove unbound molecules of the cross-linking agent from the formedchannel 26. In certain cases, removing the cross-linking agent mayreduce the potential toxicity to a patient if too much of thecross-linking agent is released from channel 26. Formed channel 26 ispreferably contacted with the quenching agent after the cross-linkingtreatment and, preferably, may be included with the washing/rinsingsolution. Examples of quenching agents include glycine or sodiumborohydride.

The formed gelatin tubes may be further treated with biologics,pharmaceuticals or other chemicals selected to regulate the body'sresponse to the implantation of channel 26 and the subsequent healingprocess. Examples of suitable agents include anti-mitolicpharmaceuticals such as Mitomycin-C or 5-Fluorouracil, anti-VEGF (suchas Lucintes, Macugen, Avastin, VEGF or steroids).

After the requisite drying period, the formed and cross-linked gelatintubes are removed from the underlying supports or wires. In oneembodiment, wire tubes may be cut at two ends and the formed gelatintube slowly removed from the wire support. In another embodiment, wireswith gelatin film thereon, may be pushed off using a plunger or tube toremove the formed gelatin channel.

FIGS. 16 and 17 show two alternative methods and apparatus for forminggelatin channels. In FIG. 16, apparatus 140 includes a suspended wire142 that may be introduced into a vacuum chamber 144 at a temperature of20° C. The gelatin solution 146 maintained at 55° C. may be applied tothe wire in vacuum chamber 144 by spraying via air jet 148. Wire 142 isrotated by rotating apparatus 150 to ensure that the sprayed gelatin isapplied evenly to the surface of wire 142.

In FIG. 17, a further alternative embodiment of forming gelatin tubes isshown. In accordance with the embodiment of FIG. 17, a wire 142 attachedto a rotating apparatus 150 is dipped into the gelatin solution 163 at55° C. as generally described above. Wire 142 is dipped into andremoved, from the gelatin solution repeatedly and sprayed with air toensure an even coat of the gelatin film onto the wire. In eitherembodiment of FIGS. 16 and 17, the gelatin tubes formed thereby may befurther subjected to a cross-linking step desired above.

The gelatin tube may also be formed by preparing the mixture asdescribed above and extruding the gelatin into a tubular shape usingstandard plastics processing techniques. Preparing channel 26 byextrusion allows for providing channels of different cross sections. Forexample, as shown in FIG. 34, channels 26 having two or more passageways260 may be provided, allowing for flow regulation. In one embodiment,passageways 260 may be selectively opened or obstructed, as shown in theshading on FIG. 34( d) to selectively control flow therethrough. One ofthe passageways 260 may be adapted to receive guidewire 28 or, in thealternative, channel 26 of FIG. 34 may be used (and implanted) without aguidewire, as previously described. Channel 26 shown in FIG. 34 may alsoprovide greater structural integrity after implantation.

FIG. 18 shows an automated apparatus 160 for preparing a plurality ofmicrofistula gelatin tubes. Shown in FIG. 18 is an apparatus 160 thatincludes a temperature controlled bath 162 of the gelatin solution 163.The apparatus includes a frame 164 that carries a vertically movabledipping arm 166. The dipping arm is coupled to a gear box 168 which isactuated by a rotary motor. The dipping arm includes a plurality ofclamps (not shown) for holding several mandrel wires 170 for dippinginto the gelatin solution. As further shown in FIG. 18, mandrel wires170 may further include weights 172 suspended at their distal ends toensure that the wire remains substantially straight (without kinking orcurving) and to dampen oscillations or vibrations when being dipped inthe gelatin solution 163. The operation of apparatus 160 may becontrolled by a controller such as a computer with commands for dippingand withdrawal of the wires from the gelatin solution. A stirrer 176 maybe provided to ensure the consistency of the gelatin solution. After thegelatin tubes have been formed, the tubes are dried and cross-linked asdescribed above.

Channels 26 made in accordance with the methods described above, allowfor continuous and controlled drainage of aqueous humor from theanterior chamber of the eye. The preferred drainage flow rate isapproximately 2 microliters per minute, although by varying the innerdiameter and length of channel 26, the flow rate may be adjusted asneeded. One or more channels 26 may be implanted into the eye of thepatient to further control the drainage.

In addition to providing a safe and efficient way to relieve intraocularpressure in the eye, it has been observed that implanted channelsdisclosed herein can also contribute to regulating the flow rate (due toresistance of the lymphatic outflow tract) and stimulate growth offunctional drainage structures between the eye and the lymphatic and/orvenous systems. These drainage structures evacuate fluid from thesubconjunctiva which also result in a low diffuse bleb, a small blebreservoir or no bleb whatsoever.

The formation of drainage pathways formed by and to the lymphatic systemand/or veins may have applications beyond the treatment of glaucoma.Thus, the methods of channel implantation may be useful in the treatmentof other tissues and organs where drainage may be desired or required.

In addition, it has been observed that as the microfistula channelabsorbs, a “natural” microfistula channel or pathway lined with cells isformed. This “natural” channel is stable. The implanted channel stays inplace (thereby keeping the opposing sides of the formed channelseparated) long enough to allow for a confluent covering of cells toform. Once these cells form, they are stable, thus eliminating the needfor a foreign body to be placed in the formed space.

While the methods, apparatus and systems of this disclosure have beendescribed with reference to certain embodiments, it will be apparent tothose skilled in the art that numerous modifications and variations canbe made within the scope and spirit of the inventions as recited in theappended claims.

1-113. (canceled)
 114. A device for deploying an intraocular shunt, thedevice comprising: a deployment mechanism; and a bent hollow shaftcoupled to the deployment mechanism, wherein the shaft is configured tohold an intraocular shunt.
 115. The device according to claim 114,wherein the bend is at a distal portion of the shaft.
 116. The deviceaccording to claim 115, wherein the bend is greater than 90°.
 117. Thedevice according to claim 115, wherein the bend is arcuate.
 118. Thedevice according to claim 114, wherein a distal end of the shaft isbeveled.
 119. The device according to claim 114, further comprising anarcuate distal portion.
 120. The device according to claim 114, furthercomprising an intraocular shunt that is at least partially disposedwithin the shaft.
 121. The device according to claim 114, wherein thehollow shaft is a needle.
 122. The device according to claim 114,wherein the shaft is disposable.
 123. The device according to claim 114,wherein the device is a handheld device.
 124. A device for deploying anintraocular shunt, the device comprising: a housing; a deploymentmechanism at least partially disposed within the housing; and a benthollow shaft coupled to the deployment mechanism, wherein the shaft isconfigured to hold an intraocular shunt.
 125. The device according toclaim 124, wherein the bend is at a distal portion of the shaft. 126.The device according to claim 125, wherein the bend is greater than 90°.127. The device according to claim 124, wherein a distal end of theshaft is beveled.
 128. The device according to claim 124, wherein thehollow shaft is a needle.
 129. The device according to claim 124,further comprising an intraocular shunt that is at least partiallydisposed within the shaft.
 130. The device according to claim 124,wherein the deployment mechanism causes retraction of the hollow shaftto thereby deploy the shunt.
 131. The device according to claim 124,wherein the housing comprises an enlarged hollow distal portion thattapers to a more narrow hollow proximal portion.
 132. The deviceaccording to claim 124, wherein the deployment mechanism includes astopper that limits axial movement of the shaft.
 133. The deviceaccording to claim 124, wherein the device is a handheld device.